Shaft bearing retainer

ABSTRACT

A retainer for holding bearings within a shaft bearing has C-shaped pockets for holding the bearings. Between the pockets are connecting portions, which are close to the openings of the pockets. The rear sides of adjacent pockets and the rear side of the connecting portion for the adjacent pockets form a concave site that is deeply gouged into the retainer. The bottom of the concave site is closer to the openings than the bottom of the pockets, thereby allowing base oil from grease in the concave site to better migrate onto the bearings and so lubricate the shaft bearing.

CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application claims the benefit of Japanese PatentApplication Serial Number 2002-319668 entitled “Shaft Bearing Retainer,”naming the same inventor, filed on Nov. 1, 2002, claiming prioritybenefits under 35 U.S.C. §119.

FIELD OF THE INVENTION

[0002] The present invention relates to shaft bearings that includebearings. More particularly, the present invention relates to retainersfor holding the bearings in the shaft bearing.

BACKGROUND OF THE INVENTION

[0003] Shaft bearings are used to constrain a rotating shaft to maintainits axis of rotation. Such shaft bearings are used in motors, such asspindle motors, commonly found in computer equipment and audio systems.A typical structure for a shaft bearing includes two rings, bearings,and a retainer. The two rings are an inner ring, having a rotationgroove on its outer surface, and an outer ring, having a correspondingrotation groove on its inner surface. The grooves and the axis ofrotation are common to the rings. Between the two rotation grooves are aplurality of bearings, sometimes called ball bearings, which are evenlyspaced apart circumferentially. The retainer is between the inner andouter rings and maintains even spacing of the bearings around thecircumference of the rings. In this manner, the inner ring rotates withrespect to the outer ring along a common axis by means of the evenlyspaced apart bearings between the rotation grooves.

[0004] One type of retainer is a crown retainer. A crown retainer istypically molded from resin into a ring shape and includes a pluralityof pockets equidistantly spaced around the circumference of theretainer. Each pocket retains a corresponding bearing to maintain theeven spacing of the bearings around the rotation grooves. The pocketsare open on one side of the retainer along the axial direction of theretainer. The inner surface of each pocket has a curvature correspondingto the curvature of the bearing.

[0005] The shaft bearing is assembled by inserting the bearings betweenthe respective rotation grooves of the outer and inner rings, andinserting the retainer between the rings to snap each bearing into itscorresponding pocket on the retainer. Upon mounting the retainer, greaseis inserted into the shaft bearing, and a shield is mounted on the shaftbearing to close the gap between the inner and outer rings.

[0006] The grease is inserted onto the retainer between the inner andouter rings. The grease is inserted from the side of the retainer thathas the pocket openings, and it is inserted onto the edge faces of theretainer between the pockets, where it adheres. A component of thegrease is a low viscosity lubricating oil, called base oil, which soaksthrough from the grease and flows into the pockets as the retainerrevolves around the axis of rotation. Since the bearings rotate in theretainer, the base oil in the interior of the pockets migrates betweenthe rotation grooves of the inner and outer rings. In this manner, thebase oil lubricates the rotation faces of the bearings in contact withthe rotation grooves.

[0007] Some shaft bearings, however, do not allow insertion of thegrease from the side of the retainer having the pocket opening. Examplesof such shaft bearings have multiple coaxial rows of bearings. One suchexample is a shaft bearing having two coaxial rows of bearings betweenthe inner and outer rings. Each row of bearings has a respectiveretainer that is inserted between the rings to snap the two rows ofbearings into place. But the pocket openings of the two retainers faceeach other in this assembly. Access to the retainers is only to therespective sides of the retainers that are opposite to the pocketopenings. As such, the grease is not near the pockets as they movearound the circumference of the grooves, and it takes a relatively longtime for sufficient base oil to reach the surface of the bearings.

[0008] In this case, the lack of sufficient lubrication reduces the lifespan of the shaft bearing or renders the shaft bearing immediatelyunusable. Moreover, the grease immediately scatters when the shaftbegins to rotate and adheres to the outer ring and shield. Achieving astable rotation with low torque is therefore difficult.

[0009] One proposed solution is to include channels between the pocketson the outer circumference of the retainer. Each channel runs betweenthe edge faces of the retainer. Either the channel holds the grease orthe grease is inserted through the channel to the pocket opening side ofthe retainer. Even so, it is difficult to align the nozzle of a greasegun with each channel, and the grease would adhere to the inner surfaceof the outer ring and not sufficiently utilize the channel.

[0010] A further proposed solution to the problems associated with thechannels in the retainer is to form a relatively elongated nozzle accessarea that leads to each channel on the edge face opposite the pocketopening. Such a nozzle access area is described in Japanese PatentPublication No. JP 8-277843. The ejection opening of the nozzle may beeasily positioned with respect to this relatively long nozzle accessarea, in contrast to the difficulty of positioning the nozzle withrespect to the channels as described above. The easy positioning allowsfor the adequate insertion of grease.

[0011] Since grease is inserted from the nozzle access area up to thechannel, however, this solution is inefficient because not all of thegrease is used. Also, flow resistance of the grease is generated as theroute traveled by the inserted grease lengthens, and the channel maystill not receive sufficient grease.

SUMMARY

[0012] A retainer for a shaft bearing is described below to address theneed for a retainer that allows base oil to reach pocket openings on theretainer, where the base oil is from grease that is applied to the edgeface of the retainer opposite the pocket openings.

[0013] One aspect of the shaft bearing retainer includes at least twopocket rings. Each pocket ring has a circumferential outer surface andan opening. The shaft bearing retainer also includes at least oneconnecting portion disposed between the two pocket rings. The connectingportion is located in close proximity to the openings of the pocketrings, and the connecting portion and circumferential outer surfaces ofthe pocket rings form a concave site.

[0014] Another aspect of the invention is a shaft bearing. The shaftbearing includes a retainer which has at least two pocket rings. Eachpocket ring has a circumferential outer surface and an opening. Theretainer also includes at least one connecting portion disposed betweenthe two pocket rings. The connecting portion is located in closeproximity to the openings of the pocket rings, and the connectingportion and circumferential outer surfaces of the pocket rings form aconcave site.

[0015] The foregoing and other features and advantages of preferredembodiments will be more readily apparent from the following detaileddescription, which proceeds with reference to the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

[0016]FIG. 1 is a longitudinal cross-sectional view illustrating a shaftbearing containing a retainer;

[0017]FIG. 2 is an overall perspective view of a preferred embedment ofthe retainer of FIG. 1;

[0018]FIG. 3 is a partial magnified side view of a preferred embodimentof the retainer of FIG. 1;

[0019]FIG. 4 is a partial magnified side view of another preferredembodiment of the retainer of FIG. 1; and

[0020]FIG. 5 is a partial magnified view of yet another preferredembodiment of the retainer of FIG. 1.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0021]FIG. 1 shows a longitudinal cross section of a shaft bearing 20that includes a shaft 10, which rotates. The shaft bearing 20 includesan outer ring 30, an inner ring 40, two rows of rolling elements such asbearings 50, and a ring-shaped retainer 60 that holds the bearings 50 ineach row. The shaft 10 has a stepped shape, having a large diameterportion 10A and a small diameter portion 10B that are coaxial to eachother. The outer circumferential face of the large diameter portion 10Ahas a rotation groove 11 along the direction of the circumference. Theouter circumferential face of the small diameter portion 10B, has aninner ring 40 affixed by means such as adhesive. The external diameterof the inner ring 40 equals the external diameter of the large diameterportion 10A of the shaft 10. The outer circumferential face of the innerring 40 has a rotation groove 41 along the direction of thecircumference. The inner circumference face of the outer ring 30 has tworows of rotation grooves 31 formed along the direction of thecircumference.

[0022] Between each rotation groove 31 of the outer ring 30 and therespective rotation grooves 11, 41 of the shaft 10 and the inner ring40, is a prescribed number of bearings 50, which are held at equalintervals in the direction of the circumference. The bearings 50 aresnapped into the retainers 60 and roll freely. Shields 51 close thespacing of both end portions of the shaft bearing 20 after grease isinserted into each retainer. The shields 51 are mounted on the innercircumferential face of the outer ring 30 by snap rings 52. In thisshaft bearing 20, the large diameter portion 10A of the shaft 10 isconstrained by the outer ring 30 by means of bearings 50 and rotatesfreely. The small diameter portion 10B is constrained by the outer ring30 by means of the inner ring 40 and the bearings 50.

[0023] The shaft bearing 20 is assembled in the following manner. Theinner ring 40 is snapped into the small diameter portion 10B of theshaft 10. The shaft 10 is inserted into the outer ring 30 and theprescribed number of bearings 50 are snapped in between the respectiverotation grooves 11 and 41 of the shaft 10 and the inner ring 40. Theretainer 60 is snapped onto the bearings 50, and the inner ring 40 isadhered to the shaft 10. After assembly, the shield 51 is mounted withthe snap ring 52.

[0024]FIG. 2 is an overall perspective view of the retainer 60 in theshaft bearing 20 of FIG. 1. The retainer is a crown type composed ofresin or other such deformable elastomeric material. It should beunderstood, however, that the present invention is not restricted toresin and that other deformable elastomeric material may be used such aspolypropylene, rubber, or polyethylene. The retainer 60 includes aplurality of pocket rings 70 disposed at equal intervals along thedirection of the circumference of the retainer 60. Connecting portions80 are disposed between these pocket rings 70, connecting the pocketrings.

[0025] The pocket ring 70 is C-shaped. The inner portion of the pocketring 70 is formed by the pocket 72, into which the bearings 50 aresnapped. An opening 72 b of the pocket 72 is open on one of the sides ofthe pocket 72 in the direction along the axial direction of the shaftretainer 60. The opening 72 b of the pocket 72 is the space between bothedges of the pocket rings 70. The pocket ring 70 includes a pair of nailportions 71 which may deform elastically on either side of the pocketopening 72 b in preference to deformation of the connecting portion 80.The pocket opening 72 b is the space between the nail portions 71. Theinternal face of the pocket 72 has a curved surface corresponding thesurface of the bearing 50 that is snapped into the retainer 60. Thebearings 50 are inserted into the retainer 60 by placing the bearing 50in contact with the tips of the nail portions 71. Each nail portion 71elastically deforms and widens to accept the bearing 50. By furtherinsertion, the bearing 50 snaps into the pocket 72. In this manner, eachbearing 50 is held at equal intervals along the circumference of theretainer 60.

[0026]FIG. 3 is a partial magnified side view of a preferred embodimentof the retainer 60. The rear face side of the retainer 60 is defined asthe side opposite to those of the pocket openings 72 b. On the rear faceside are concave sites 61, formed between adjacent pocket rings 70. Eachconcave site 61 is defined by the arc-shaped outer circumferential faces73 of adjacent pocket rings 70 and an edge face 81 of the rear face sideof the connecting portion 80. The bottom of the concave site 61 is theedge face 81, which is closer to the pocket opening 72 b than the bottomportion 72 a of the pocket 72. Further, the thickness of the pocket ring70 decreases on moving around the pocket 70 from the bottom portion 72 ato the nail portion 71.

[0027] Each of the two rows of bearings 50 is mounted with a respectiveretainer 60. The bearings 50 are snapped in between each rotation groove31 of the outer ring 30 and the respective rotation grooves 11, 41 ofthe shaft 10 and the inner ring 40. As shown in FIG. 1, each retainer 60is oriented such that the pocket openings 72 b of each retainer 60 areopposed to each other. After mounting each retainer 60, grease isinserted into each concave site 61 from the rear face side of theretainer 60.

[0028] Edge face 81 of connecting portion 80 forms the bottom of theconcave site 61 on the rear face side of the retainer 60. This edge face81 is nearer the pocket opening 72 b than the bottom portion 72 a of thepocket 72 as shown in FIG. 3. In other words, the concave sites 61 aredeeply scooped out of the rear-face side of the retainer 60. Further,because the thickness of the pocket rings 70 decreases going around thepocket ring 70 from the bottom portion 72 a, through the connectingportion 80, to the nail portion 71, the circumferential length 73 of theconcave site 61 may be increased as compared to the length for auniformly thick pocket ring 70.

[0029] With this configuration, a relatively large quantity of greasemay be inserted into and held in the concave site 61. As the retainer 60revolves around the shaft 10, the pocket 72 may receive adequate baseoil from the grease at the bottom of the concave site 61, i.e. edge face81, to lubricate the bearings 50 because the edge face 81 is nearer tothe pocket opening 72 b as described above. Moreover, the greaseinserted into the concave site 61 does not easily adhere to the outerring 30, the inner ring 40, the shaft 10, and the shield 51. Thus baseoil may lubricate the bearings 50 immediately upon the rotation of theshaft 10, increasing the life span of the shaft bearing 20 andpermitting the rotation with low torque.

[0030]FIG. 4 is a partial magnified side view of another preferredembodiment of the retainer 60B. The retainer 60B includes planes 75formed on the edge portions of the outer circumferential face 73 of thepocket ring 70 that forms the concave site 61, towards the center 74 ofthe pocket ring 70. This embodiment of the retainer 60B may bemanufactured by injection molding of resin into metal molds. If the twometal molds separate axially, i.e. separate axially along acircumferential line, the molds may be simplified by matching theparting line of the molds with the edge face 81, or having the partingline of the molds cross the planes 75. Further, the pouring gate of themold may be set on the edge face 81 on the rear face side of theretainer 60B.

[0031]FIG. 5 is a partial magnified side view of yet another preferredembodiment of the retainer of 60C. The retainer 60C includes a channel84 between the edge faces 81, 82 of the connecting portion 80. Thechannel 84 is formed on the outer circumferential face 83 of theconnecting portion 80. Grease is inserted into the concave site 61 andis held in the channel 84. The channel 84 supplies base oil to theinterior of the pocket 72, improving lubrication of the bearing 50 thatis snapped into the pocket 72.

[0032] In general, the present invention permits the introduction oflarge quantities of grease onto the rear face side of the retainer60-60C, opposite the pocket opening 72 b side of the retainer 60-60C,for lubricating the bearings 50 and rotation grooves of the shaftbearing 20. It should be understood, however, that the present inventionis not limited to the embodiments described above and that otherconfigurations of the concave site 61 are possible for holding grease inclose proximity to the pocket opening 72 b, such as closer to the pocketopening 72 b than the bottom portion 72 a of the pocket 72.

[0033] The foregoing detailed description is merely illustrative ofseveral physical embodiments of the invention. Physical variations ofthe invention, not fully described in the specification, may beencompassed within the purview of the claims. Accordingly, any narrowerdescription of the elements in the specification should be used forgeneral guidance, rather than to unduly restrict any broaderdescriptions of the elements in the following claims.

I claim:
 1. A shaft bearing retainer comprising: at least two pocketrings, each pocket ring having a circumferential outer surface and anopening; and at least one connecting portion disposed between the twopocket rings, wherein the connecting portion is located in closeproximity to the openings of the pocket rings, and wherein theconnecting portion and circumferential outer surfaces of the pocketrings form a concave site.
 2. The shaft bearing retainer of claim 1,wherein a bottom of the concave site is closer to the openings of thepocket rings than bottom portions of the pocket rings.
 3. The shaftbearing retainer of claim 1, wherein each of the pocket rings furthercomprises an inner surface having a shape complimentary to the shape ofa rolling element of the shaft bearing.
 4. The shaft bearing retainer ofclaim 1, wherein the concave site is configured to accommodatelubricating material.
 5. The shaft bearing retainer of claim 1, whereineach of the pocket rings further comprises two walls, each of the wallshaving a thickness gradually diminishing towards the opening of thepocket ring.
 6. The shaft bearing retainer of claim 1, wherein each ofthe pocket rings further comprises at least one slanted plane extendingbetween a predetermined point on the circumferential outer surface andthe connecting portion.
 7. The shaft bearing retainer of claim 6,wherein the slanted plane further comprises an inclination angle.
 8. Theshaft bearing retainer of claim 1, wherein the connecting portionfurther comprises an upper edge, a bottom edge, and a channel, andwherein the channel extends from the upper edge to the bottom edge. 9.The shaft bearing retainer of claim 1, wherein each of the pocket ringsfurther comprises at least one cut-off surface located at the opening ofthe pocket ring, and wherein the cut-off surface is deformable towardsthe opening of the pocket ring.
 10. The shaft bearing retainer of claim1, wherein the retainer is composed of a deformable elastomericmaterial.
 11. The shaft bearing retainer of claim 10, wherein theelastomeric material is resin.
 12. A shaft bearing having a retainer,wherein the retainer comprises: at least two pocket rings, each pocketring having a circumferential outer surface and an opening; and at leastone connecting portion disposed between adjacent pocket rings, whereinthe connecting portion is located in close proximity to the openings ofthe pocket rings, and wherein the connecting portion and circumferentialouter surfaces of the pocket rings form a concave site.
 13. The shaftbearing of claim 12, wherein a bottom of the concave site is closer tothe openings of the pocket rings than bottom portions of the pocketrings.
 14. The shaft bearing of claim 12, wherein each of the pocketrings further comprises an inner surface having a shape complimentary tothe shape of a rolling element of the shaft bearing.
 15. The shaftbearing of claim 12, wherein the concave site is configured toaccommodate lubricating material.
 16. The shaft bearing of claim 12,wherein each of the pocket rings further comprises two walls, each ofthe walls having a thickness gradually diminishing towards the openingof the pocket ring.
 17. The shaft bearing of claim 12, wherein each ofthe pocket rings further comprises at least one slanted plane extendingbetween a predetermined point on the circumferential outer surface andthe connecting portion.
 18. The shaft bearing of claim 17, wherein theslanted plane further comprises an inclination angle.
 19. The shaftbearing of claim 12, wherein the connecting portion further comprises anupper edge, a bottom edge, and a channel, and wherein the channelextends from the upper edge to the bottom edge.
 20. The shaft bearing ofclaim 12, wherein each of the pocket rings further comprises at leastone cut-off surface located at the opening of the pocket ring, andwherein the cut-off surface is deformable towards the opening of thepocket ring.
 21. The shaft bearing retainer of claim 12, wherein theretainer is composed of a deformable elastomeric material.
 22. The shaftbearing retainer of claim 12, wherein the elastomeric material is resin.